This present invention relates to an electronic metronome and more particularly to a metronome having a visual and/or audio displaying device.
Conventional visual tempo-displaying devices, i.e., metronomes, display tempos with a lamp turning on and off in correspondence with a tempo signal generated from a tempo signal generator. In this conventional metronome, the tempo signal applied to the lamp of the metronome is produced by differentiating the tempo signal generated from the tempo signal generator by means of a differential cirucit. As the differential circuit has a predetermined time constant, the output signal rise time of the tempo signal generated from the differential circuit is constant irrespective of the various frequencies of the tempo signals. Generally, a music tempo if 40 to 208 beats per minute, the periods of which are 1.5 to 0.288 second .Accordingly, if the time constant of the differential circuit is determined with respect to the tempo signal of 208 beats per minute so that it is easy to see the flash of light of the tempo signal and if the same time constant is also used with respect to the tempo signal of 40 beats per minute, the duty time of the lower tempo signal (40 beats per minute) differentiated by the differential circuit is very small in comparison with that of the higher tempo signal (208 beats per minute). It will be noted that the duty time is the proportion of the pulse signal rise time to its fall time of the tempo signal. As the result, a output signal rise time of the tempo signal (40 beats per minute) is too short to display the tempo signal with the light turning on and off because the on-time of the light is very short, and so, it is difficult that a singer, a musical instrument player, etc. precisely see the tempo signal.
On the other hand, in the condition that the time constant of the differential circuit and the duty time of the tempo signal generated from the differential circuit are determined with respect to the lower tempo signal (40 beats per minute) so that it is easy to see the tempo signal, when the higher tempo signal (208 beats per minute) is applied to the differential circuit of the same time constant, the duty time of the output signal generated from the differential circuit is too long to display the tempo signal with the light, so that it is difficult that the singer, the player, etc. precisely see the tempo signal.
Accordingly, the duty time of the tempo signal generated from the differential circuit is predetermined corresponding to the various tempos considering the ability of a person to precisely see the tempo signal by the flashing of a light.
It had not been known that the electronic metronome has a duty time setting circuit producing the tempo signal having the duty time which is constant irrespective of the various tempo signal.